In short: Magnesium citrate is magnesium bound to citrate, the salt of citric acid. Trimagnesium dicitrate is the precise chemical name for the usual form. Citrate dissolves well in water and is better absorbed in studies than magnesium oxide. Magnesium contributes to normal muscle function. You'll tolerate it best in small portions with food.
Key points
- Three names, mostly one substance: magnesium citrate, magnesium dicitrate and trimagnesium dicitrate almost always mean the same compound in shops.
- How much magnesium is in it: anhydrous trimagnesium dicitrate contains 16.2% magnesium, the hydrated form around 11.9% (our calculation from the molar masses).
- Good absorption: in several studies, more magnesium reached the body from citrate than from magnesium oxide.
- Benefits: Magnesium contributes to normal functioning of the nervous system. Magnesium contributes to a reduction of tiredness and fatigue.
- Take it comfortably: with food and split across two meals. Only larger amounts taken at once make stools softer.
- Citrate or glycinate: both are among the well-absorbed forms.
Contents
- What is magnesium citrate?
- Magnesium citrate, magnesium dicitrate, trimagnesium dicitrate: what is the difference?
- How well is magnesium citrate absorbed?
- Citrate, oxide, glycinate or malate: which is best?
- Benefits: what is magnesium citrate good for?
- Why does magnesium citrate have a laxative effect?
- Powder, capsules or tablets?
- How do you take magnesium citrate?
- Quality and storage
- Frequently asked questions
- Limits of the research and all sources
What is magnesium citrate?
Magnesium citrate is a salt of magnesium and citric acid, the acid you know from citrus fruits. In it, magnesium is bound to citrate, the remainder of the acid. The result is a white powder that dissolves well in water.
So what's the difference between "magnesium" and "magnesium citrate"? Pure magnesium is a metal that nobody eats. In supplements, magnesium is always bound in a compound, for example as citrate, oxide or glycinate. The "magnesium" figure on the pack states only the mineral's share of that compound.
What the studies show: The European Food Safety Authority (EFSA) describes trimagnesium dicitrate as the magnesium salt of citric acid, which fully breaks down into magnesium and citrate after swallowing. Both occur naturally in food and in the body anyway.4
Magnesium citrate, magnesium dicitrate, trimagnesium dicitrate: what is the difference?
Usually none. The names describe the same compound with different levels of precision. "Trimagnesium dicitrate" counts it out: three magnesium to two citrate. "Magnesium dicitrate" is a shortened form of this, "magnesium citrate" the umbrella term.
There is a real difference, though, and it lies in the water. Trimagnesium dicitrate is sold anhydrous or with water built into the crystal. That water adds to the weight, so the magnesium share falls. Rarer still is a citrate with only one magnesium per citrate (magnesium hydrogen citrate).
| Compound | Formula | Molar mass | Magnesium content |
|---|---|---|---|
| Trimagnesium dicitrate, anhydrous | Mg₃(C₆H₅O₇)₂ | 451.12 g/mol1 | 16.2% |
| Trimagnesium dicitrate nonahydrate (9 water) | Mg₃(C₆H₅O₇)₂ · 9 H₂O | 613.25 g/mol2 | 11.9% |
| Magnesium hydrogen citrate | MgC₆H₆O₇ | 214.41 g/mol3 | 11.3% |
Magnesium content: our calculation from the molar masses in the PubChem substance database.
How to do it: This is how the percentages come about. One magnesium atom weighs 24.305 units.1
- Anhydrous trimagnesium dicitrate: 3 × 24.305 = 72.9. Divided by 451.12, that's 16.2%.
- With 9 crystal water molecules: 72.9 divided by 613.25 is 11.9%.
For your pack, that means: 1,000 mg of anhydrous trimagnesium dicitrate provides at most around 162 mg of magnesium. If a pure citrate states clearly more than 16.2%, something chemically different has been added.
What the studies show: One preparation in a large comparative study was labelled with 15.5% magnesium. That's just under the calculated maximum of 16.2%, so it's consistent with pure citrate.5
How well is magnesium citrate absorbed?
Well, and in most studies better than magnesium oxide. Citrate already dissolves in water. Oxide needs a lot of stomach acid to dissolve and still remains partly undissolved. What doesn't dissolve, the gut can't absorb.
What the studies show: In a lab test, 55% of the citrate dissolved in pure water alone, compared with barely any of the oxide. After a large single dose, urinary magnesium rose considerably more with citrate.6 Two more recent studies in healthy men confirm this: after 300 mg and 400 mg of magnesium respectively, participants excreted more magnesium in their urine with citrate than with oxide, a common measure of absorption.7, 8
The difference also shows over longer periods. In a study of 46 healthy adults, participants took 300 mg of magnesium a day for 60 days. Blood magnesium rose most with citrate; oxide did not differ from placebo.9 In a 24-week study of 164 older adults, blood levels rose similarly with citrate, oxide and sulfate. In urine, though, more magnesium came through with citrate.5 A systematic review of 14 comparative studies sums it up: organic forms such as citrate are absorbed better than inorganic ones such as oxide, and the share absorbed falls as the amount increases.10
Beyond the form, the individual product matters too: 15 commercially available preparations dissolved very differently in the lab. The worst of them was also absorbed markedly less well in people.14
Our take: Most human studies clearly favour citrate over oxide, both over short and longer periods. If you're looking for a well-dissolving, well-absorbed form, citrate is a very good choice. What matters most for your supply is then that you take it regularly, in portions of up to 250 mg of magnesium a day, with food.
Citrate, oxide, glycinate or malate: which is best?
Citrate is, along with glycinate, one of the well-absorbed forms. Which of the two you take is mainly a question of tolerability and capsule size. Oxide contains a lot of magnesium per gram, but less of it is absorbed. Malate has barely been studied in people so far.
| Form | Magnesium content | Absorption in studies | Tolerability |
|---|---|---|---|
| Citrate | 11–16% (depending on water content) | better than oxide7, 9, 10 | loose stools from larger amounts20, 22 |
| Oxide | high, a lot of magnesium per capsule | worse than organic forms10 | fewer gastrointestinal complaints than citrate in one long-term study5 |
| Glycinate | 14.1% at most | inconsistent compared with citrate9, 13 | considered gentle on the stomach |
| Malate | depends on the form | good in rats15 | not yet compared in people |
What the studies show: In the 60-day study, both citrate and an amino acid chelate did better than oxide in urine. In blood, citrate came out ahead.9 In another study, blood magnesium rose after a portion of citrate but not measurably after bisglycinate.13 In experiments with gut cells, on the other hand, bisglycinate came out ahead.12 Both forms are therefore a good choice. You'll find the same conclusion in our article on magnesium glycinate.
In rats, blood levels stayed raised longest with malate; citrate performed more weakly there.15 These are early indications from animal studies. You'll find an overview of all forms in Which magnesium is best?
Benefits: what is magnesium citrate good for?
Magnesium citrate gives you magnesium in a well-absorbed form. That means everything officially confirmed for magnesium applies to citrate too. Among others, the EU has authorised these statements:
- Magnesium contributes to normal muscle function.
- Magnesium contributes to normal functioning of the nervous system.
- Magnesium contributes to normal psychological function.
- Magnesium contributes to a reduction of tiredness and fatigue.
- Magnesium contributes to normal energy-yielding metabolism.
- Magnesium contributes to electrolyte balance.
For people who exercise, muscle function, energy metabolism and electrolyte balance are especially relevant. A daily portion of citrate with food fits well into a training routine.
One study using exactly this form comes from migraine research.
What the studies show: Researchers studied 81 adults with migraine. For twelve weeks, they took 600 mg of magnesium a day as trimagnesium dicitrate or a dummy pill. In weeks 9 to 12, the number of migraine attacks fell by 41.6% in the magnesium group and by 15.8% in the placebo group. The number of days with migraine and the amount of painkillers used per person also fell in the magnesium group, a statistically significant result.22 This amount is far above the upper limit for food supplements. Anyone with migraine should discuss this with their doctor first.
Magnesium citrate is also often taken for night-time leg cramps. In a study on this, 46 adults took 300 mg of magnesium as citrate. Cramps tended to decrease, and more participants felt it had helped.17
Our take: Magnesium citrate is a good form for supplying yourself with magnesium every day, whether in daily life or during exercise. Take up to 250 mg of magnesium a day with a meal and stick with it over weeks. Whether citrate does more for cramps or sleep than other forms is something larger studies still need to show.
Why does magnesium citrate have a laxative effect?
Because magnesium that the gut doesn't absorb holds on to water. That makes stools softer. The typical side effects are loose stools, diarrhoea and bloating, less often a feeling of pressure in the stomach. This is almost always down to the amount you take at once.
Medicine puts exactly this property to use: for bowel cleansing before examinations, magnesium citrate is used in amounts of several grams. That's many times what's in a daily portion of a food supplement.
What the studies show: Magnesium salts hold water in the gut and make its contents more liquid.20 Studies on bowel cleansing used 17.7 or 35.4 g of magnesium citrate at once.21 With 600 mg of magnesium a day as trimagnesium dicitrate, 18.6% of participants got diarrhoea.22 With 450 mg of magnesium as citrate over 24 weeks, on the other hand, participants had no more gastrointestinal complaints than with placebo. With oxide, there were slightly fewer still than with citrate in this study.5
Tip: If your stomach rebels, split the amount across two meals and take it with food. If that doesn't help, cut back the amount for a few days. The European Food Safety Authority sets the upper limit for magnesium from supplements at 250 mg a day, precisely because of possible digestive complaints.23
An analysis of more recent studies found no difference in diarrhoea for many magnesium supplements compared with placebo, even at amounts above this limit.24 The limit is therefore a cautious guideline, not a value beyond which problems are guaranteed.
Important: If your kidney function is reduced, magnesium can build up in the body.25 Talk to your GP first in that case. This applies especially to the large amounts of magnesium citrate used in laxatives.
Powder, capsules or tablets?
Take the form you're most likely to take regularly. Powder can be dosed finely and dissolves in a glass of water. Capsules are tasteless and easy to take with you. With effervescent and chewable tablets, it's worth checking the ingredient list, because they can contain sugar, sweeteners or flavourings.
When comparing, only one figure counts: how much magnesium is in a portion, not how much citrate. An example for 250 mg of magnesium:
| Form of citrate | Amount needed for 250 mg magnesium |
|---|---|
| Anhydrous trimagnesium dicitrate (16.2%) | around 1.55 g |
| Trimagnesium dicitrate nonahydrate (11.9%) | around 2.1 g |
Our calculation from the molar masses.1, 2
That's why citrate capsules are often large or you need several of them. That's not a quality flaw, it's chemistry: citrate simply weighs more than oxide.
What the studies show: How well a preparation dissolves in the stomach strongly influences absorption, regardless of the form stated on the label.14
How do you take magnesium citrate?
Take it with a meal and, from supplements, stick to no more than 250 mg of magnesium a day unless your doctor says otherwise. Split anything above about 250 mg across two meals. The time of day is secondary. What matters is taking it every day.
If the pack states "400 mg magnesium" a day or "high strength", that's often above this upper limit. If you have a product like that, split the daily amount or take less.
What the studies show: We've summarised how amount, time of day and meals affect absorption in When should you take magnesium? How much magnesium you need overall is covered in How much magnesium per day?
You need a gap from some medicines. With the thyroid hormone levothyroxine, magnesium citrate reduced absorption by 7% in a small study. The difference was not statistically reliable, but the researchers still advise leaving a gap.26 You'll find the details on antibiotics and osteoporosis medicines in the section on interactions.
Magnesium citrate can be combined with other supplements. Make sure the magnesium from all your products doesn't add up beyond the upper limit. A multivitamin often already contains magnesium.
Quality and storage
A good citrate product clearly states how much magnesium is in each portion and, ideally, the amount of citrate too. Then you can use the calculation above to check whether the figures add up. Lab reports on heavy metals are good to have, but they say nothing about whether citrate is genuinely in there.
Store powder and capsules dry, at room temperature and well sealed. Keep them out of reach of children.
And: supplements are no substitute for a varied diet. Nuts, wholegrains, legumes and green vegetables also provide magnesium.
Frequently asked questions
What is the difference between magnesium and magnesium citrate? Magnesium is the mineral, magnesium citrate one of its compounds. In supplements, magnesium is always bound in a compound. The "mg magnesium" figure states only the mineral's share.
Is trimagnesium dicitrate good or bad? Is it harmful? It's a well-studied, well-absorbed form. The European Food Safety Authority saw no safety concerns at usual amounts and points to the upper limit of 250 mg of magnesium a day.4 The most common side effect is loose stools from larger amounts. With kidney disease, only after talking to your doctor.25
Trimagnesium dicitrate or magnesium citrate: which should I take? These are usually the same thing. Compare the amount of magnesium per portion, not the name.
How quickly does magnesium citrate work? Blood levels rise slightly within the first few hours.27 It takes around 20 weeks to settle at a new level.28 Take it regularly over several weeks for this reason.
Does magnesium citrate help with heartburn? It isn't intended for that. An acid-neutralising effect has been described for other magnesium salts, such as magnesium hydroxide.20 If you have frequent heartburn, talk to your GP.
Magnesium citrate or magnesium glycinate? Both are absorbed better than oxide and are a good choice.9, 13 If citrate gives you loose stools, you could try glycinate instead.
Can I take magnesium citrate at night? Yes. The time of day makes little difference to your supply. A second portion fits well with your evening meal if you're splitting the daily amount.
Is the magnesium citrate powder in supplements the same as the liquid solution used for bowel cleansing? Both contain magnesium citrate, but the amounts are completely different. For magnesium from supplements, the upper limit is 250 mg a day.23 In studies on bowel cleansing, 17.7 or 35.4 g of magnesium citrate were used in one go.21 That is a medical use before examinations, not a daily supplement dose.
Limits of the research and all sources
Most comparisons measure absorption via urine or blood levels after a single portion. That says little about your supply over months. Several studies were funded by manufacturers, and for others the funding isn't public. Which water content the citrate in these studies had is rarely stated.
There are contrary findings on absorption too: in a ten-day study of 61 young women, an oxide powder improved blood levels more than citrate.11 In experiments with gut cells, citrate did no better than oxide.12 We haven't found direct comparative studies on the tolerability of citrate and glycinate, and for malate there are only animal studies.15 We also haven't found studies specifically on the citrate form in sport.
For cramps and sleep, there are only a few small studies with citrate and no clear benefit. In 45 adults with night-time leg cramps, citrate brought no fewer cramps than a dummy pill.16 The trend in the second cramp study was not statistically reliable.17 A Cochrane review concludes that magnesium probably brings no noticeable benefit for cramps in older people.18 In 100 adults over 51 with poor sleep, sleep improved just as much with 320 mg of magnesium as citrate as with placebo.19 The migraine study is a single study from 1996 with 600 mg of magnesium, far above the upper limit for supplements. The duration and severity of attacks did not change to a statistically significant degree.22
Show all 28 sources
| # | Study | Who was studied | Result | Strength of evidence |
|---|---|---|---|---|
| 1 | PubChem CID 6099959 and CID 5462224 | Substance database | Trimagnesium dicitrate 451.12 g/mol, magnesium 24.305 → 16.2% | Reference data |
| 2 | PubChem CID 53249332 | Substance database | Nonahydrate 613.25 g/mol → 11.9% | Reference data |
| 3 | PubChem CID 8949 | Substance database | Magnesium hydrogen citrate 214.41 g/mol → 11.3% | Reference data |
| 4 | EFSA 2016, EFSA Journal | Regulatory opinion on trimagnesium dicitrate | breaks down into magnesium and citrate; no concerns at usual amounts | Official assessment |
| 5 | Schutten et al. 2022, J Am Heart Assoc | 164 older adults, 450 mg/day, 24 weeks | blood levels similar to oxide, more in urine; complaints like placebo, slightly more than oxide | Controlled study, partly co-funded by a magnesium manufacturer |
| 6 | Lindberg et al. 1990, J Am Coll Nutr | Solubility lab test + healthy adults | citrate more soluble, more magnesium in urine than oxide | Lab + small study |
| 7 | Kappeler et al. 2017, BMC Nutr | 20 healthy men, 300 mg single dose | more magnesium in urine and blood than oxide | Controlled study, manufacturer study (citrate) |
| 8 | Werner et al. 2019, Magnes Res | 14 healthy men, 400 mg single dose | more magnesium in urine and blood than oxide | Small study, funding not disclosed |
| 9 | Walker et al. 2003, Magnes Res | 46 healthy adults, 300 mg/day, 60 days | citrate highest blood level; citrate and chelate better than oxide in urine | Controlled study, funding not disclosed |
| 10 | Pardo et al. 2021, Nutrition | 14 comparative studies | organic forms better than inorganic, share absorbed falls with amount | Systematic review |
| 11 | Ivanovic et al. 2022, BioMetals | 61 young women, 10 days | oxide powder improved blood levels more than citrate | Small study, contrary finding |
| 12 | Hartle et al. 2016, FASEB J | Gut cells in the lab, 5 forms | bisglycinate ahead, citrate level with oxide | Cell study |
| 13 | Pajuelo et al. 2024, Nutrients | 40 healthy adults, one portion each | blood level rose after citrate, not measurably after bisglycinate | Controlled study, manufacturer study of a competing form |
| 14 | Blancquaert et al. 2019, Nutrients | 15 preparations in the lab, 30 people | dissolution and absorption varied widely by product | Lab + small study |
| 15 | Uysal et al. 2018, Biol Trace Elem Res | Rats, 5 forms | malate longest in blood, citrate weak | Animal study |
| 16 | Frusso et al. 1999, J Fam Pract | 45 adults with leg cramps | citrate no better than placebo | Small controlled study |
| 17 | Roffe et al. 2002, Med Sci Monit | 46 adults, 300 mg as citrate | trend to fewer cramps, not statistically reliable | Small controlled study |
| 18 | Garrison et al. 2012, Cochrane | 7 studies, 406 people | no noticeable benefit for cramps in older people | Systematic review |
| 19 | Nielsen et al. 2010, Magnes Res | 100 adults over 51, 320 mg as citrate, 7 weeks | sleep improved equally in both groups | Controlled study |
| 20 | Izzo et al. 1996, Magnes Res | Review | magnesium salts bind water in the gut; hydroxide neutralises acid | Review |
| 21 | Hoy et al. 2009, Drugs | Review on bowel-cleansing agents | 17.7 or 35.4 g magnesium citrate for bowel cleansing | Review |
| 22 | Peikert et al. 1996, Cephalalgia | 81 adults with migraine, 600 mg as trimagnesium dicitrate, 12 weeks | attacks −41.6% (placebo −15.8%) in weeks 9–12; diarrhoea in 18.6% | Controlled study |
| 23 | EFSA / SCF 2001 | Regulatory opinion | upper limit 250 mg/day from supplements | Official assessment |
| 24 | Costello et al. 2023, Adv Nutr | 10 studies since 1997 | mostly no difference in diarrhoea vs placebo | Review with commentary |
| 25 | Rosner et al. 2023, Mayo Clin Proc | Review | build-up with reduced kidney function | Review |
| 26 | Attinger et al. 2025, Clin Transl Sci | 15 healthy adults | thyroid hormone: 7% less absorption with citrate (not statistically reliable) | Small |
| 27 | Wilimzig et al. 1996, Eur J Clin Pharmacol | Healthy adults, trimagnesium dicitrate | blood level rises a few percent within 12 hours | Small study |
| 28 | Zhang et al. 2016, J Nutr | 48 studies, 2,131 people | blood level stable after around 20 weeks | Meta-analysis |
Author: PRONESIUM Editorial Team · Last reviewed: 29/09/2026 · This article does not replace medical advice.
